# Copyright 2023 The HuggingFace Team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import tempfile
import unittest

import pytest
import torch
from datasets import Dataset
from transformers import AutoModelForSequenceClassification, AutoTokenizer, EvalPrediction

from trl import RewardConfig, RewardTrainer
from trl.trainer import compute_accuracy

from .testing_utils import require_peft


class RewardTrainerTester(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        cls.model_id = "trl-internal-testing/dummy-GPT2-correct-vocab"
        cls.model = AutoModelForSequenceClassification.from_pretrained(cls.model_id)
        cls.tokenizer = AutoTokenizer.from_pretrained(cls.model_id)
        cls.tokenizer.pad_token = cls.tokenizer.eos_token

    def test_accuracy_metrics(self):
        dummy_eval_predictions = EvalPrediction(torch.FloatTensor([[0.1, 0.9], [0.9, 0.1]]), torch.LongTensor([0, 0]))
        accuracy = compute_accuracy(dummy_eval_predictions)
        assert accuracy["accuracy"] == 0.5

    def test_reward_trainer(self):
        with tempfile.TemporaryDirectory() as tmp_dir:
            training_args = RewardConfig(
                output_dir=tmp_dir,
                per_device_train_batch_size=2,
                max_steps=3,
                remove_unused_columns=False,
                gradient_accumulation_steps=4,
                learning_rate=9e-1,
                eval_strategy="steps",
            )

            # fmt: off
            dummy_dataset_dict = {
                "input_ids_chosen": [
                    torch.LongTensor([0, 1, 2]),
                    torch.LongTensor([1, 2]),
                    torch.LongTensor([0, 1, 2]),
                    torch.LongTensor([1, 2]),
                ],
                "attention_mask_chosen": [
                    torch.LongTensor([1, 1, 1]),
                    torch.LongTensor([1, 0]),
                    torch.LongTensor([1, 1, 1]),
                    torch.LongTensor([1, 0]),
                ],
                "input_ids_rejected": [
                    torch.LongTensor([0, 2]),
                    torch.LongTensor([1, 2, 0]),
                    torch.LongTensor([0, 2]),
                    torch.LongTensor([1, 2, 0]),
                ],
                "attention_mask_rejected": [
                    torch.LongTensor([1, 1]),
                    torch.LongTensor([1, 1, 0]),
                    torch.LongTensor([1, 1]),
                    torch.LongTensor([1, 1, 1]),
                ],
            }
            # fmt: on
            dummy_dataset = Dataset.from_dict(dummy_dataset_dict)

            trainer = RewardTrainer(
                model=self.model,
                args=training_args,
                tokenizer=self.tokenizer,
                train_dataset=dummy_dataset,
                eval_dataset=dummy_dataset,
            )

            previous_trainable_params = {n: param.clone() for n, param in trainer.model.named_parameters()}

            trainer.train()

            assert trainer.state.log_history[(-1)]["train_loss"] is not None

            # check the params have changed
            for n, param in previous_trainable_params.items():
                new_param = trainer.model.get_parameter(n)
                # check the params have changed - ignore 0 biases
                if param.sum() != 0:
                    assert not torch.equal(param, new_param)

            preds = trainer.predict(dummy_dataset)
            assert preds.predictions.shape == (4, 2)

    @require_peft
    def test_reward_trainer_peft(self):
        from peft import LoraConfig, TaskType

        peft_config = LoraConfig(
            task_type=TaskType.SEQ_CLS,
            inference_mode=False,
            r=8,
            lora_alpha=32,
            lora_dropout=0.1,
        )

        with tempfile.TemporaryDirectory() as tmp_dir:
            training_args = RewardConfig(
                output_dir=tmp_dir,
                per_device_train_batch_size=2,
                max_steps=6,
                remove_unused_columns=False,
                gradient_accumulation_steps=2,
                learning_rate=9e-1,
                eval_strategy="steps",
            )

            # fmt: off
            dummy_dataset_dict = {
                "input_ids_chosen": [
                    torch.LongTensor([0, 1, 2]),
                    torch.LongTensor([1, 2]),
                    torch.LongTensor([0, 1, 2]),
                    torch.LongTensor([1, 2]),
                ],
                "attention_mask_chosen": [
                    torch.LongTensor([1, 1, 1]),
                    torch.LongTensor([1, 0]),
                    torch.LongTensor([1, 1, 1]),
                    torch.LongTensor([1, 0]),
                ],
                "input_ids_rejected": [
                    torch.LongTensor([0, 2]),
                    torch.LongTensor([1, 2, 0]),
                    torch.LongTensor([0, 2]),
                    torch.LongTensor([1, 2, 0]),
                ],
                "attention_mask_rejected": [
                    torch.LongTensor([1, 1]),
                    torch.LongTensor([1, 1, 0]),
                    torch.LongTensor([1, 1]),
                    torch.LongTensor([1, 1, 1]),
                ],
            }
            # fmt: on
            dummy_dataset = Dataset.from_dict(dummy_dataset_dict)

            trainer = RewardTrainer(
                model=self.model,
                args=training_args,
                tokenizer=self.tokenizer,
                train_dataset=dummy_dataset,
                eval_dataset=dummy_dataset,
                peft_config=peft_config,
            )
            previous_trainable_params = {}
            previous_non_trainable_params = {}

            # due to a change in the way the modules to save are dealt in PEFT.
            trainable_params_name = ["lora", "modules_to_save"]

            # check gradients are not None
            for n, param in trainer.model.named_parameters():
                if any(t in n for t in trainable_params_name):
                    previous_trainable_params[n] = param.clone()
                else:
                    previous_non_trainable_params[n] = param.clone()

            trainer.train()

            assert trainer.state.log_history[(-1)]["train_loss"] is not None

            # check the params have changed
            for n, param in previous_trainable_params.items():
                new_param = trainer.model.get_parameter(n)
                assert not torch.allclose(param, new_param, atol=1e-12, rtol=1e-12)

            # check the non trainable params have not changed
            for n, param in previous_non_trainable_params.items():
                new_param = trainer.model.get_parameter(n)
                assert torch.allclose(param, new_param, atol=1e-12, rtol=1e-12)

            preds = trainer.predict(dummy_dataset)
            assert preds.predictions.shape == (4, 2)

    def test_reward_trainer_assert_value_error(self):
        with tempfile.TemporaryDirectory() as tmp_dir:
            training_args = RewardConfig(
                output_dir=tmp_dir,
                per_device_train_batch_size=2,
                max_steps=1,
                remove_unused_columns=False,
            )

            # fmt: off
            dummy_dataset_dict = {
                "input_ids_b": [
                    torch.LongTensor([0, 1, 2]),
                    torch.LongTensor([1, 2]),
                    torch.LongTensor([0, 1, 2]),
                    torch.LongTensor([1, 2]),
                ],
                "attention_mask_c": [
                    torch.LongTensor([1, 1, 1]),
                    torch.LongTensor([1, 0]),
                    torch.LongTensor([1, 1, 1]),
                    torch.LongTensor([1, 0]),
                ],
                "input_ids_f": [
                    torch.LongTensor([0, 2]),
                    torch.LongTensor([1, 2, 0]),
                    torch.LongTensor([0, 2]),
                    torch.LongTensor([1, 2, 0]),
                ],
                "attention_mask_g": [
                    torch.LongTensor([1, 1]),
                    torch.LongTensor([1, 1, 0]),
                    torch.LongTensor([1, 1]),
                    torch.LongTensor([1, 1, 1]),
                ],
            }
            # fmt: on
            dummy_dataset = Dataset.from_dict(dummy_dataset_dict)

            trainer = RewardTrainer(
                model=self.model,
                args=training_args,
                tokenizer=self.tokenizer,
                train_dataset=dummy_dataset,
            )

            with pytest.raises(ValueError):
                trainer.train()

            training_args = RewardConfig(
                output_dir=tmp_dir,
                per_device_train_batch_size=2,
                max_steps=1,
                remove_unused_columns=True,
            )

            with self.assertWarns(UserWarning):
                trainer = RewardTrainer(
                    model=self.model,
                    args=training_args,
                    tokenizer=self.tokenizer,
                    train_dataset=dummy_dataset,
                )

    def test_reward_trainer_margin(self):
        with tempfile.TemporaryDirectory() as tmp_dir:
            training_args = RewardConfig(
                output_dir=tmp_dir,
                per_device_train_batch_size=2,
                max_steps=3,
                remove_unused_columns=False,
                gradient_accumulation_steps=4,
                learning_rate=9e-1,
                eval_strategy="steps",
            )

            # fmt: off
            dummy_dataset_dict = {
                "input_ids_chosen": [
                    torch.LongTensor([0, 1, 2]),
                ],
                "attention_mask_chosen": [
                    torch.LongTensor([1, 1, 1]),
                ],
                "input_ids_rejected": [
                    torch.LongTensor([0, 2]),
                ],
                "attention_mask_rejected": [
                    torch.LongTensor([1, 1]),
                ],
                "margin": [
                    torch.FloatTensor([1.0]),
                ]
            }
            # fmt: on
            dummy_dataset = Dataset.from_dict(dummy_dataset_dict)

            trainer = RewardTrainer(
                model=self.model,
                args=training_args,
                tokenizer=self.tokenizer,
                train_dataset=dummy_dataset,
                eval_dataset=dummy_dataset,
            )

            batch = [dummy_dataset[0]]
            batch = trainer.data_collator(batch)
            loss, outputs = trainer.compute_loss(trainer.model, batch, return_outputs=True)

            l_val = -torch.nn.functional.logsigmoid(
                outputs["rewards_chosen"] - outputs["rewards_rejected"] - batch["margin"]
            ).mean()

            assert abs(loss - l_val) < 1e-6

    def test_reward_trainer_tags(self):
        with tempfile.TemporaryDirectory() as tmp_dir:
            training_args = RewardConfig(
                output_dir=tmp_dir,
                per_device_train_batch_size=2,
                max_steps=3,
                remove_unused_columns=False,
                gradient_accumulation_steps=4,
                learning_rate=9e-1,
                eval_strategy="steps",
            )

            # fmt: off
            dummy_dataset_dict = {
                "input_ids_chosen": [
                    torch.LongTensor([0, 1, 2]),
                    torch.LongTensor([1, 2]),
                    torch.LongTensor([0, 1, 2]),
                    torch.LongTensor([1, 2]),
                ],
                "attention_mask_chosen": [
                    torch.LongTensor([1, 1, 1]),
                    torch.LongTensor([1, 0]),
                    torch.LongTensor([1, 1, 1]),
                    torch.LongTensor([1, 0]),
                ],
                "input_ids_rejected": [
                    torch.LongTensor([0, 2]),
                    torch.LongTensor([1, 2, 0]),
                    torch.LongTensor([0, 2]),
                    torch.LongTensor([1, 2, 0]),
                ],
                "attention_mask_rejected": [
                    torch.LongTensor([1, 1]),
                    torch.LongTensor([1, 1, 0]),
                    torch.LongTensor([1, 1]),
                    torch.LongTensor([1, 1, 1]),
                ],
            }
            # fmt: on
            dummy_dataset = Dataset.from_dict(dummy_dataset_dict)

            trainer = RewardTrainer(
                model=self.model,
                args=training_args,
                tokenizer=self.tokenizer,
                train_dataset=dummy_dataset,
                eval_dataset=dummy_dataset,
            )

            assert trainer.model.model_tags == trainer._tag_names
